1. Field of the Invention
This invention relates to a protected converter arrangement, consisting of electronic power circuitry with controlled valves and information-processing electronic circuitry for controlling the valves.
2. Discussion of the Prior Art
Converter arrangements using controlled valves, for instance, rectifiers, DC (chopper) controllers, inverters, AC controllers and semiconductor switches are usually equipped with thyristors or transistors. The use of such semiconductor components of the power type ensures high operating reliability in such converters. The high operating reliability of thyristor inverters has led to increasing employment of static converters in protected power supply installations instead of the rotating converters customary up to now. For consumers having still more stringent requirements, power supplies for completely interruption-free service in which several static converters operate in parallel are being built. Several such plant concepts are described in the journal "Energie und Technik", 1971, pages 61 to 64.
When several inverters having a central control unit are operated in parallel, the inverters which are connected in parallel on the output side are controlled by a common control unit. This technique provides only little security against a total failure.
In parallel operation with a central synchronizing oscillator, several complete inverters are synchronized by a central oscillator. The assurance against total failure is already very high here, since only the failure of the central oscillator can lead to total failure.
Even higher reliability against total failure is offered by redundant partial-load operation, there being no central equipment in which a disturbance can result in a total failure. With this technique, several completely independent inverters influence each other to a limited degree. They operate normally with partial load. In the event of a disturbance, the disturbed equipment is discovered by monitoring devices and is disconnected. The entire consumer load is taken over by the equipments which continue to operate.
In known converter arrangements having several converters operating in parallel, the high investment costs are a disadvantage. In addition, high losses are incurred continuously, as in undisturbed operation, the individual converters operate only in the partial load range.
It is an object of the invention to provide a protected converter arrangement for supplying uninterrupted power to a consumer which is distinguished by low investment costs and low operating costs.